Brake-equalizing mechanism



March 8, 1927.

P. D. BARRETT BRAKE EQUALIZING MECHANISM 2 Sheets-Sheet 1 Filed June 15, 1925 March 8,1927.

F'. D. BARRETT BRAKE E uALIzIm MECHANISM Filed June 15. 192:5 2 Sheets-Sheet 2 1 00/ A Bar/eff Patented Mar. 8, 1927.

PATENT OFFICE.

ram. 1). BARRETT, or SAN raimcrsoo, cumonma.

BBAKE-EQUALIZING MECHAN 15E.

Application filed June 15, 1925. Serial No. 37,810.

This invention relates to improvements in brake equalizing mechanism for automobile brakes and the like. and particularly o improvements in means for equalizing brakes upon one pair of wheels and simultaneously maintaining a desired ratio of braking pressures between the one pair of wheels ano another pair of wheels; furthermore, to equalize the braking pressure of each pail respectively and simultaneously maintain an equal or diflerential ratio between the total pressures imparted by the respective pairs of brakes.

The primary object of my invention is to provide an improved mechanism for regulating the pressures imparted by a plurality of brakes upon an antomobile or the like.

Another object is to provide an improved device for equalizing pressure imparted by one pair of brakes and simultaneously maintaining a ratio between said pressure and the pressures imparted by the other brakes of the vehicle.

A further object is to provide an improved means for preventing the failure of one pair of brakes from causing the failure'of the other brakes on the vehicle.

A still further object is to provide an improved device for varying the ratio of the total pressure imparted by one pair of brakes to the pressures imparted by the other brakes during the progress of application.

I accomplish these and other objects by means of the device disclosed in the drawings forming a part of the present specification wherein like characters of reference are used to designate similar parts throughout said specification and drawings and in which,

'Fig. 1 is :1 Ian view of the major compensating device. The letters a, b, and a, will be used to designate the respective arms of this device.

Fig. 2 is a cross sectional view of the aforesaid major compensating device showing a method of connecting the main pull rod to said major compensating device. and also a method of connection of the pull rod 6 from the equalizer bar 9 shown in Fig. 4, to the a arm of the major compensating device.

Fig. 3 is a detail view showing the nature of the hooks formed on the ends'of the b and 0 arms of the major compensating connection of pull sure supplied by the other pair of brakes during application of the brakes and of acting as a stop in the event of failure of one pair of brakes due to a severance or accidental disconnection of the linkage between the major compensating device 4 and either the front or the rear pair of brakes.

Fig. 6 isa cross sectional view of a fluid operated device for varying the ratio of the total pressure applied by one pair of brakes to the total pressure applied by the other pair of brakes.

Fig. 7 is a modified form of linkage similar to that shown in Fig. 4, but utilizing a one piece rock shaft.

Referring to the drawings it will be noted that no chassis or braking members are shown and it is assumed to be obvious that this mechanism may be adapted to any type of braking member and frame construction, and that while I have referred generally to pairs of brakes. the mechanism is equally applicable to a single brake. such as a transmission or propeller shaft brake, or to any combination 0 brakes, either singly or in pairs, or both.

The numeral 1 is used to designate in genera] a brake pedal or common operatin means having a lever 2 connected to a pull rod 3 which in turn is suitably connected to a major compensating device 4 having arms a, b, and c, the angular difi'erence of said arms (a, b, and a) being preferably, 120 degrees each from the others. At suitable points on the arms a, b, and c, the pull rods 6, 7, and 8 respectively, are operably connected. The opposite end of the pull rod 6 is rotatably connected to the center of the equalizer 9. Said equalizer 9 is connected at its ends to similar levers 10 which are mounted upon adjacent ends of the rock shafts 11. The opposite ends of the rock shafts 11 have mounted upon them the levers 12 which are similar to the levers 10 but point in the opposite direction. The pull rods 13 are'connected to the levers 12 for transmitting the braking force to the front brakes. The pull rods 7 and 8 are connected at their opposite ends to similar levers 1 t mounted upon adjacent ends of the rock shafts 15 which have similar levers 16 mounted on their opposite ends and pointing in the same direction as the levers 14. The pull rods 17 are connectedto the levers 16 for transmitting the braking force to the rear brakes.

Taking upthe description of the stop and ratio varying device 5 as shown in Fig. 5, the screw 18 asses through a corresponding- 1y threaded liole in the stationary member 19 and has a lock nut 20 to secure its position at any desired setting. Around the body of the screw 18 passes an open helical spring 21, one end of which abuts against the stationary member 19 and the other end thereof abuts against the movable member 22 whose movement is limited by the pin 23 and the slot 24.

In operation the brakes are operated by depressin the foot pedal in the well known manner, the movement of the pedal operating to impart movement through the lever 2 and the rod 3 to the major compensating device 4. The major compensating device 4 in turn imparts movement to the equalizer 9 through the rod 6. The movement imparted to the equalizer 9 is transmitted through the levers 10, rock shafts 11. levers 12 and pull rods 13 to actuate the front brakes. The pivotal connection of the rod 6 with the center of the equalizer 9 and the hook and eye connections of the levers 10 with the ends of said e ualizer causes the front brakes to be actuate to apply the same degree of pressure. The major compensating device 4 also im arts movement to the rock shafts 15 througi the pull rods 7 and 8 and the levers 14 said movement being further transmitted through the levers 16 and pull rods 17 to actuate the rear brakes. By virtue of the freedom of movement permitted to the major compensatin device 4 by the connections of the pull r0 s 3, 6, 7, and 8 thereto, the total force imparted to said major compensating device is divided be tween the arms a. b, and c in inverse proportion to the distances of the respective points of connection of the pull rods 6. 7, and 8 from the point of connection of the main pull rod 3.

In the event of failure of any part of the operating linkage connecting the front pair of brakes with the major compensating device 4 the consequent forward movement of the a arm of said major compensating device would be arrested by the movable member 22 of the stop and ratio varying device 5, said member 22 acting as a fulcram, thereby permitting the major compensating device 4 to perform the dual function of acting as a lever and equalizer to transmit force to actuate the rear pair of brakes. Likewise, in the event of the failure of any part of the qperating linkage connecting the rear pair 0 brakes with the major compensating device 4, the consequent backward movement of the (1 arm of said major compensating device would be arrested by the stationary member 19 of the stop and ratio varying device 5, said member 19 acting as a fulcrum, thereby permitting the major compensating device 4 to act as an ordinary lever to transmit force through the pull rod 6 and equalizer 9 to actuate the front brakes. Hence, the failure of one pair of brakes causing the failure of the other brakes on the vehicle is prevented.

By adjustment of the screw 18 of the stop and ratlo varying device 5, the movable member 22 of said device can be made to come into contact with the a arm of the major compensating device 4 at a predetermined point along the forward travel of said arm, the further application of the brakes will cause the spring 21 to counteract a portion of the force received by the a arm of the major compensating device and in effect transfer said portion of the force in equal proportions to the b and 0 arms of the major compensating device. Hence, the variation of the ratio of the pressure imparted by one pair of brakes to the pressures imparted by the other brakes of the vehicle during progress of application can be accomplished.

In Fig. 6 is shown a device using fluid. preferably oil, which may take the place of the mechanical stop and ratio varying device 5. This modification preferably comprises a closed, fluid filled cylinder 25 suitably attached to a stationary part of the vehicle and provided with a suitable piston and associated rod 26 formed to engage the arm a of the major compensating device 4., The piston is provided with two apertures, one of which acts together with a ball 27, as a check valve permitting free fluid flow when the piston moves from left to right, in Fig. 6, and no fluid flow when the piston moves in the opposite direction. The fluid is consequently constrained to flow thru the other aperture 29 when the piston moves from right to left in response to application of the brakes. A wedge 28 is disposed in the cylinder and extends thru the aperture 29 so that as the brakes are applied the fluid flow is gradually restricted an an increasing resistance is offered to the movement of arm a. The 510 e of the wedge 28 may be varied 0r curve to give any desired size to the aperture 29 at various piston positions. A dashpot effect is also secured with the fluid device, as a uiflis gs. t pdevlcfs,

use its seeds ts filial-"ta i1 0 felt a MP? v a reprises its til s-'11 ti! lever e0!!- all red. 6. fear ba e iii of reek Shaft lLl veirS I will sacrum th 1 l mit manates to s for ti??? intautm r i he'- appl-i y the rafile now (011 b lims f my that th de e 'n (1e13,, the referred em- ?e'ntion, it is-underst'ood 37 mo ified in va ious way bo h a its const u ti n of the se ral par 's l ef [e se as to the i ran'eem n ith t d partin from t s'j'g it of my in'v ties I djo not wish to r an at mys lf a ly e' lie Pr c e die i 95!?? made, but i 'h t an my l of al sueh'modffieations as may fall within the sc pe of the'ap'p'ended claims.

Having thus defswib 'd y invention hat I claim as newa d desire to secure by leap P ents,

' 1. four wheel brake pressure compens tting" mechanism with transmission, from 3 common operating member through said p nsating mechani m to? th b ki ineu' bers of all ten; wheels, said compensat- 'ng m chani m comp g a for na'lizing" between one air of brakes and s multaneously maintainfng a ratio of brak'ng pressures between the two pairs of other pair of brakes, and a means for varybrakes.

2. A four wheel brake pressure com.

' pensating mechanism with transmission from a commonfoperating member through said compensating mechanism to the braking members of all four wheels, said compensating mechanism comprising an equalizer for one pair of brakes, and a unitary means for equalizing between the other air of brakes and simultaneously maintaining a ratio of braking pressures between the two pairs of brakes;

3. A four wheel brake pressure compensating mechanism with transmission from a common operating member through said compensating mechanism to the braking members of all four wheels, said compensatt d a i d ib d unita y m ans "as a unitary r at.

v.l ails, sa d amp at: P -esteem gam s a s sta equalizing bet theotpair fbra and simu ta eou ly maintains a rati 0t b k n P s t s between he we a f rak s; and a mean forflpr en nig the f il re f one ai failure of the ot er air of brakes.

5- A e w eel, b aka er iir mm nestins m h n ith we em ssi n" m a common operating r thr u Said compensating machain 'sm to the (raking m ers of ll foi Wh 6l aid wmp n ing .i necha-nism comprising a means for e ual zing tweeq 9. s flair of br kes and simultaneously maintaining a ratio of bra-ks pr e b we n th wo Pairs of brakes, a means for preventing the failure of one pair of brakescausing the failure of the other-pair 'o f brakesand lmeans for varyin the ratio of the to ressure applie' by one pair oi brakes to tie totalpressure ap lied bythe other-pair of brakes during, app ication of the'brake's.

. 6. four wheel brake ressure com ensating mechanism with transmission rom a common 0P i %1 member through said compensating mec anism to the raking members'of all four wheels, said compensatmg mechanism oomprisin an equalizer for one pair of brakes, a means for equalizing between the other pair of brakes and simultaneously maintaining a ratio of braking pressures between the two pairs, of brakes,

a means for preventing the failure of one pair of brakes causing the failure of the ing the ratio of the total'pressure applied by one pair of brakes to the total presure applied by the other pair of brakes'during application of the brakes.

7. In a brake mechanism, a brake pull rod, three secondary pull rods, and a unitary compensating device connected to said for distributing the motion of said brake pull rod to said secondary pull rods.

8. In a brake mechanism, a brake pull rod, and a compensating device having three arms for transmitting the pull of said brake pull rod to secondary pull rods attached to said three arms.

9. In a brake mechanism, a unita compensating device having three radia arms,

'Of brakes causing the rods universally qna'ec a brake pu llirod the cent-qr all said dev arms.

IO In' brake -II,1el1 rod, :1 compensating e vel sally mounted at its center big sald pu three secondary pill-l.

brake pull rod} and unii g'z a to said compensating device points;

11. In a brake mecl1an i$rh,1- a lllllllt gily omnpe'nsating device having tlniee arms, 'a brake pull rod connected to said device; secondary pull rogls'iconngted tbsaid-arms; andlmans 1x5 f0 r' aligning; a yielding resistance the mqtioaof onea bfsaidil-rms- 12. 'In' a, brake ni'gchanisrh, a: bmkQ- ullrod, and a compensating device liavin Y K Y {tee arms for attahmentfiasecqndaryj pa l 136(13, 20 r av Planqor said ai ms Being gontained in the ans 'p'fplums substanhally normal tq I said Brake pull rod.

In witness" whereof I hereunto sat my signature. 7 .San Francisco, California, June 9th,- 1925;

PAUL D. BARRETT.

pull rods connected to said arms, and means for offering a yielding resistance to the motion of one of said arms.

12. In a brake mechanism, a brake pull rod, and a compensating device having three arms for attachment to secondary pull rods, said arms bein contained in a plane or planes substantlally normal to the axis of said brake pull rod.

In witness whereof I hereunto set my signature.

San Francisco, California, June 9th, 1925.

PAUL D. BARRETT.

Certificate of Correction.

Patent No. 1,619,912.

Granted March 8, 1927, to

PAUL 1). BAR RETT.

It is hereby certified that error appears in the printed specification of the abovenumbered patent requiring correction as follows: Page 1, line 67, for the word supplied read applied; and that the said Letters Patent should he read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 26th day of April, A. D. 1927.

[sun] M. J. MOORE,

Acting Commissioner of Patents.

Certiheaie. of Correction Patent No. 1,619,912. Granted March 8, 1927, to

' mun n. BAlHiE'iT.

It is hereby certified that error appears in the printed specification of the abovenumbered patent requiring correction as follOWs: Pa e 1, line 67, for lhe word supplied read applied; and that, the said Letters iatent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of April, A. D. 1927.

[sun] M. J. MOORE,

' Acting Commissioner of Patents. 

